LANCASTER — For the first time in the Big League Western Regionals, the Antelope Valley 18-under all-star softball team was stretched past five innings.

That challenge suited McKenzie Draper just fine Monday night.

Draper, a Rosamond graduate, retired 20 in a row — including 10 strikeouts — and finished with a two-hitter without walking a batter against Portland, Ore., to lead Antelope Valley to a 9-0 semifinal victory at West Lancaster Little League Field.

Antelope Valley will face Eastside Little League of Baldwin Park — a 15-3 semifinal winner over Washington — at 8 p.m. today in the first game of the best-of-three regional championship series.

Draper, headed to Kansas Wesleyan, surrendered a bloop infield single to Kimberly Espinoza that was just out of the reach of Justeene Tamayo at shortstop to lead off the game and didn’t allow another hit until Katie Atkinson lined a two-out single to right in the seventh.

She struck out five in a row during one stretch in the second and third innings and hasn’t allowed a run in 14 regional innings, including five no-hit innings in Saturday’s 25-0 pool-play victory over Washington and another two in a 30-0 win over Arizona.

Draper also helped herself at the plate with two hits and a run. Shannon Cobbett ran for Draper in the fifth and scored as part of Antelope Valley’s five-run inning.

Marissa Harmon hit her fifth home run in regional competition to increase the lead to 4-0 in the third for Antelope Valley, which has outscored regional opponents 64-0.

Harmon, a sophomore at Adams State, also had a two-run single in the first, scoring Dani Nabors and Draper. The Highland graduate also reached base on an error in the fifth and scored.

Cobbett scored Antelope Valley’s third run on an Oregon throwing error.

Antelope Valley batted through the lineup in the fifth, with Nabors, Draper, Kylie Rawlins and Celeste Mackelrath all recording singles, in addition to Tamayo collecting a bloop double just inside the left-field line.

Melissa Munoz and Toni Hutnick both drove in runs in the fifth on sacrifice flies.

Draper, Harmon, Mackelrath and Nabors all had two hits for Antelope Valley, which collected 11 against Oregon pitcher Kelcy Brown.

Oregon had only one runner advance into scoring position, with Kimberly Espinoza moving to third in the first inning following a sacrifice bunt from Erika Espinoza and a groundout by Madison Hamilton.

Draper got Atkinson to fly out to right to end the threat. Atkinson was forced at second in the seventh to end the game.